This is a known problem and (probably) there are systems which should monitor automated abuse of abuse.
However, all those social networks (including Instagram) are susceptible to another attack - just rent a horde of low-grade bots... and add the victim's account to their friends. This sudden increase in friends count are treated as an attempt to boost the rating of the bot accounts => ban not only for the bots (about whom you don't care) but for the victim too.
Perhaps OP is in the similar situation, though probably his spouse wasn't a target but a collateral.
However, all those social networks (including Instagram) are susceptible to another attack - just rent a horde of low-grade bots... and add the victim's account to their friends. This sudden increase in friends count are treated as an attempt to boost the rating of the bot accounts => ban not only for the bots (about whom you don't care) but for the victim too.
Perhaps OP is in the similar situation, though probably his spouse wasn't a target but a collateral.